Activate device when computer starts
Most network devices will have this box checked, but you should leave it unchecked for unused devices and for devices that are used only in certain contextsfor example, a wireless card on a laptop that is used only at home.
Allow all users to enable and disable this device
If selected, this feature enables any user to activate or deactivate the network device without the root password.
Enable IPv6 configuration for this interface
If your network supports IP version 6 (which is rare but becoming more common), select this box.
IP address settings
These fields replicate the fields used during the initial device setup.
Changing the hostname field and then saving the network configuration will prevent you from opening any new GUI applications because the X Window System uses the hostname in the security key used to control access to the display. To correct this problem, log out and then log in again after changing the hostname, or enter this command before doing so:$xhost +localhost
For single-gateway networksincluding most home and office networksuse the Default Gateway field on the Devices tab and do not fill in any information on the Route tab.
Figure 3-13. Routing configuration
To add a new route, click the Edit button, then enter the network to be routed as an IP network address and a netmask, and then enter the Gateway ( router) to which packets destined for that network are to be sent.
Figure 3-13 shows a new routing entry for an 8-bit subnet: the network number is 172.16.4.0, and the netmask is 255.255.255.0, which means that any packets addressed to an IP address that starts with 172.16.4 must be sent through the gateway associated with this route, which has been set to 172.16.97.200.
The gateway must be on the same subnet as the network interface device.
for that name, it would be looked up as bluesky.fedorabook.com .
The Hosts tab shown in Figure 3-16 is used to configure static mappings , which define the relationship between hostnames and IP addresses without using DNS. This is useful if you have only a handful of hosts and wish to refer to them by hostname without going to the trouble of configuring a DNS nameserver.
Figure 3-16. Hosts tab
To add a static mapping, click the New button, and then enter the IP address, hostname, and (optionally) any aliases or alternate hostnames for that particular IP address. In Figure 3-16 , the address 172.16.97.143 is being associated with the hostname darkday.fedorabook.com as well as the (shorter) alias of just darkday . Click OK to save the mapping.
As you would expect, the Edit and Delete buttons may be used to change or remove a selected static mapping.
Do not delete the entry for 127.0.0.1 or ::1, or your system will not work properly. Both the system's hostname and localhost must appear as the hostname or alias for this entry. If you change this entry and save the configuration, it may not be possible to open new programs on the graphical display until you log out and then log in again.
3.2.1.1.3. Saving and using the network configuration
To enable or disable network interfaces, go to the Devices tab ( Figure 3-6 ), select the interface you wish to change, and click Activate or Deactivate. Alternately, you can exit from the network configuration tool and restart the Network service graphically (see Lab 4.6, "Managing and Configuring Services ") or by entering this command:
# service network restart
Shutting down interface eth0: [ OK ]
Shutting down loopback interface: [ OK ]
Bringing up loopback interface: [ OK ]
Bringing up interface eth0: [ OK ]
Network interface devices which are set to activate at boot will automatically start up when the network interface is started. Other devices may be started and stopped using the network configuration tool.
However, if the option labeled "Allow all users to enable and disable the device" has been set in the interface device configuration ( Figure 3-12 ), any user can activate or deactivate the device using the GNOME menu option ApplicationSystem ToolsNetwork Device Control (in KDE, SystemNetwork Device Control).
This option may not appear on your GNOME menu; to make it available, right-click on the GNOME application menu and select Edit Menus. Figure 3-17 shows the menu editor that appears.
Figure 3-17. The GNOME menu editor
Select ApplicationsSystem Tools in the left pane, select the checkbox labeled Network Device Control in the right pane, and then click on the Close button.
When you start the Network Device Control program, either through the menu or by typing system-control-network in a shell, the window shown in Figure 3-18 will appear.
Figure 3-18. Network Device Control window
To activate or deactivate network interface devices using this program, select the interface and click on the Activate or Deactivate buttons. Click Close when you are done with the window.
You can also activate and deactivate network interfaces from the command line using the ifup and ifdown commands: